Of all the coaches Scott Fujita was around during his 11-year NFL career -- including innovators such as Sean Payton and defensive coordinator Gregg Williams with the New Orleans Saints -- he said Rob Ryan struck him as the one who thrived the most on studying opponents' tendencies and trying to exploit them.

"Rob is sort of that mad scientist type, staying up late, working through the night drawing up crazy schemes," said Fujita, who said he enjoyed playing under Ryan with the Cleveland Browns in 2010.

Fujita served as the Browns' defensive signal caller while playing a variety of linebacker positions. And he helped collaborate on the unconventional "amoeba" scheme that Ryan used that season to cause fits for the Saints' high-powered offense in a stunning upset in the Superdome, with all 11 defensive players standing up at times to disguise their intentions.

"I think if you kind of let Rob do his thing, he's gonna mix it up every single down, personnel running on and off the field, trying to match all the changing personnel groups that we see from offenses throughout the NFL every week," Fujita said. "That's really Rob's specialty. He recognizes tendencies. He stays up all night studying that kind of stuff."

Ryan couldn't argue with the description.

Defensive coordinator Rob Ryan talks to the defense during practice at Saints headquarters in Metairie on Sunday, July 28, 2013. (Michael DeMocker, Nola.com / The Times-Picayune)

"I definitely pride myself in that," said Ryan, who took over the Saints' defense this year after both ended last season on the NFL's scrap heap (Ryan fired by the Dallas Cowboys and the Saints having broken the league record for yards allowed in a season).

"I want our team to be the best prepared team we can be," Ryan continued. "You want to try and put our guys in the best situation we can be. And to me that takes a lot of film study. And that's something I've always prided myself in, that I'm willing to work and whatever it takes.

"So I don't have much of a social life after that."

'Nothing he won't do'

Ryan's current and former players, his coaching colleagues and scouting analysts from around the league all are in agreement that his scheme's most recognizable tendency is that he doesn't have a recognizable tendency.

There's no simple formula he has relied on
throughout his 16 years in the NFL and 11 years in the college ranks.

"I think first of all, it's very multiple," Saints safety Jim Leonhard said. "It's not a system where it's, 'This is who we are, this is all we do,' like a Tampa 2 kind of system. He's very flexible."

"A lot of different variations," Saints guard Ben Grubbs said.

Payton said preparing to face Ryan's defenses always required the Saints' offense to spend extra time going over multiple looks in walk-through sessions during the practice week.

"A lot of time and detail in covering how you handle each defensive look," Payton said. "Typically, he will do a good job of trying to take away what he thinks you do well. And (you need to understand) that he's going to pay attention to who is going to get the ball on third down, where you go in the red zone, what type of runs you want to run. And you just need to self-scout and make sure there are no heavy tendencies."

We've already seen that multiplicity from Ryan's defense throughout this summer.

He often uses four safeties on the field at once in his nickel and dime packages -- sometimes removing the defensive tackle and an inside linebacker, but other times replacing an end or outside linebacker.

It's not uncommon to see just one lineman on the field, with his hand on the ground, or none at all.

A stat by the Football Outsiders scouting service illustrates Ryan's elusive tendencies.

Although he's known as an aggressive, attacking blitzer (his Browns led the NFL in rushing five players or more in 2010), Ryan's defenses have also ranked first or second in the NFL in sending only three rushers or less at the quarterback in each of the past three years.

"He'll rush three and drop eight a lot," Fujita said. "But the way that you're rushing, three might even look like a blitz."

"Ryan might have the widest array of schematic wrinkles in all of football," said Andy Benoit, who analyzes the NFL for the Football Outsiders scouting service and Sports Illustrated, among other outlets. "Really there's nothing he won't do."

The family business

Ryan, 50, agrees with the notion that his defensive signature is hard to identify -- or at least that it's not worth trying.

"I believe it's not the position of the players on the field, it's the disposition," said Ryan, who is clearly inspired most by his legendary father Buddy Ryan.

"The greatest defensive coach that ever coached is my dad. I don't care who you say. Though (Pittsburgh Steelers coordinator) Dick LeBeau is giving him a little run for his money," Ryan said of his father, who orchestrated some of the NFL's all-time great defenses, including the Super Bowl-champion Chicago Bears in 1985 and New York Jets in 1969. "He's pretty damn special. Kind of like Bill Walsh was to offense."

Buddy Ryan became famous for confusing opposing offenses with his "46" zone blitzing scheme in Chicago -- which would typically line up eight players near the line of scrimmage, often in lopsided formations, and vary what players rushed and who dropped into coverage.

In that sense, Ryan's defensive approach is very reminiscent of his father's. But it's hardly a clone.

For one thing, Buddy used a base 4-3 alignment, while Rob prefers a 3-4. Plus, Rob has had to adapt to modern, pass-happy NFL offenses that feature much more exotic formations.

Rob's defensive approach is also similar in many ways to that of his twin brother Rex, the head coach of the New York Jets (though Leonhard, who played for Rex, said the Jets' coach is more of a, 'This is what we do' guy than Rob).

And Rob is influenced by the "old-school" 3-4 defensive approach he learned under Bill Belichick when he was the New England Patriots' linebackers coach from 2000-03 and later as coordinator under Eric Mangini in Cleveland.

But Rob's defense is a mutation from all of them.

For instance, when he inherited smaller, more athletic nose tackle Jay Ratliff in Dallas, Ryan featured more of an attacking front instead of the traditional big body in the middle trying to occupy two gaps at once.

In that sense, he's a lot like Wade Phillips, one of the best defensive minds in the game today, who helped turn around Sunday's preseason opponent, the Houston Texans, with a switch to a 3-4 scheme in 2011.

Like Phillips, Ryan has definitely strayed from that old-school 3-4 approach that requires jumbo defensive linemen and heavy thumpers at inside linebacker. Most of the league is straying from it now, too.

"He's adapted," said former NFL scout Daniel Jeremiah, who now analyzes the league for the NFL Network.

Jeremiah believes Ryan will continue to do that in New Orleans -- playing to the strengths of players like defensive end Cam Jordan and outside linebacker Junior Galette (whom he believes are rising stars), versatile rookie safety Kenny Vaccaro (a good fit for Ryan's multiple schemes) and veteran outside linebacker Will Smith (a questionable fit in the open field but still valuable as a pocket pusher), among others.

"The interesting thing to me is I think his defense is unique in that it's kind of in the middle of the Patriots' 3-4, which he has experience in, and the Ryan 46, which Rex kind of took to the overaggressive level," Jeremiah said. "Kind of that middle ground of that disciplined and amoeba."

Brandt, for the record, likes the Ryan hire in New Orleans quite a bit.

"I think they hired the right guy at the right time," Brandt said. "That's a very good move they made."

Brandt still lives in the Dallas area and remains very plugged in to the Cowboys organization. So he's well aware of the ways that Ryan fell short of lofty expectations in Dallas, leading him to be fired after just two seasons and replaced by veteran Monte Kiffin and a new 4-3 system.

But as Brandt pointed out -- and as Ryan himself has pointed out several times this summer -- Ryan was hamstrung by an avalanche of injuries to the Cowboys' defense last year.

And Brandt said that Cowboys owner Jerry Jones still "thinks the world of" Ryan.

Former Cowboys defensive coordinator Rob Ryan on the sidelines during the game between the New Orleans Saints vs. Dallas Cowboys at Dallas Cowboys Stadium on Sunday, December 23, 2012. (Photo by Michael DeMocker, NOLA.com | The Times-Picayune)

"Go through the league and ask, 'What do you think of anybody? What do you think of Sean?' I don't think you'll get 100 percent of the people saying he's great or he's the answer to your problem," Brandt said. "But I think every place (Ryan) has gone, he's made the defense better. I think the guy has the ability to get the best out of people. He's really smart."

Ryan's detractors will quickly point out that none of his defenses with the Oakland Raiders (2004-08), Browns (2009-10) and Cowboys (2011-12) ever made the playoffs. And only one of them ranked in the top 10 in yards allowed (the Raiders, No. 3 in 2006).

But Ryan has earned that reputation for making bad defenses better -- especially in Oakland and Cleveland, which were in dire straits when he arrived. The Saints are hoping for that same effect after such a dreadful performance last year.

Brandt said the one criticism with Ryan is that he'll tend to try and introduce too many new wrinkles into the defense -- something Payton might have to help him edit in New Orleans.

That criticism has followed Ryan throughout his career, that his "mad scientist" schemes are sometimes too complicated and too undisciplined. That was a popular refrain in Dallas last year -- especially when he wasn't producing turnovers. So the scheme couldn't even be couched as high risk, high reward.

As Jeremiah pointed out, however, that is a generalization that isn't completely fair to Ryan.

"My take on that is for the most part is whether you're in a static defense or in a moving defense with a lot of personnel groups, you're gonna have blown coverages with both," Jeremiah said. "When it looks chaotic, then the defensive coordinator gets blamed. When it's a static formation, the players get blamed."

Still, Ryan and his players admitted there is a fine line between implementation and complication, and that Ryan has to be able to judge how much he can throw at them.

"I've had to (scale back) before. Whatever it is, to slow people down," said Ryan, who has also been frank about his need to earn his respect in New Orleans after being humbled in Dallas.

At the same time, Ryan has also been repeatedly frank about how much confidence he has in his abilities.

"I think we've all been criticized. I'm sure you (in the media) have been criticized. I'm sure you do a great job and everybody knows it. But there'll be some critic out there," Ryan said. "But I don't care about critics. I just want to do a great job here. I just want to be a little tiny part of our success here. We've got a great organization, and I just gotta do my tiny little part."

Maximizing 'buy-in'

Ryan has never faced much criticism from players about the size of his playbook. Fujita said he enjoyed making all those checks and audibles in Cleveland, even when it required six, eight or even 10 adjustments at the line of scrimmage.

Leonhard, who has played for Rex in Baltimore and New York, said the same thing.

It can be taxing, both players said. But it can be worth it.

"There is absolutely (a risk of trying to do too much). But as players, you have to take that responsibility," Leonhard said. "You always hate being on a defense where you know you have weaknesses, and maybe they come out in a certain formation and you know what's happening and you can't stop it. But when you have a lot on your plate and you can make adjustments and get yourself out of bad situations, you love that as a player. Because you're gonna make a team beat you.

"It does put a lot on the players, and you have to be locked in every play. But you like it that way. You'd rather have it that way."

There are several other things that Fujita and current players have said they love about playing for Ryan. They believe that Ryan will do a good job of playing to their strengths (a plus for rising young athletes and a must for veteran players with limited skill sets like Smith, safety Roman Harper and linebacker Jonathan Vilma). Players also know that because of the multiple packages and looks, they will have a role somewhere.

They've also talked about having a voice and input in Ryan's defense, that he listens to their suggestions and makes adjustments accordingly.

Many of those were traits that Saints players also embraced in former coordinator Williams but found lacking last year in coordinator Steve Spagnuolo.

Fujita also said he believes Ryan genuinely loves his players and has emotional ties to them, similar to Saints assistant head coach Joe Vitt in that sense.

"That all maximizes 'buy-in' from the players," Fujita said. "I didn't get to watch a whole lot of Saints defense last year, but one of the things I sensed was that there wasn't a whole lot of buy-in to the defense.

"If you don't have the buy-in, then you have nothing."

Ryan said his ever-evolving defense is more than happy to let the players have input, which he said he and his brother learned from their dad.

"We know we're good and we're confident, but we're smart and we don't mind sharing anything," Ryan said. "When you have smart veteran players and they're seeing things differently, they're the ones on the field. I made one tackle in 16 years in this league. And that was (LaDanian Tomlinson) out of bounds because no one else would tackle him that day.

"I think the better teacher you are, the more input you can handle. I don't have a damn dictatorship in my room. I just want it to look right on Sundays."